class Loan {
    var expiryDate: String?
    var maturityDate: String?

    func capital() -> Double {
        if expiryDate != nil && maturityDate != nil {
            return 10.0 * duration() * riskFactor()
        }
        if expiryDate != nil && maturityDate == nil {
            if getUnusedPercentage() > 1.0 {
                return 150.0 * getUnusedPercentage()
            } else {
                return 200.0 * getUnusedPercentage()
            }
        }

        return 0.0
    }

    func duration() -> Double {
        return 0.0
    }

    func riskFactor() -> Double {
        return 0.0
    }

    func getUnusedPercentage() -> Double {
        return 5.0
    }
}